There were unconfirmed reports that at least 150 people had died in the quake, a spokesman for the International Committee for the Red Cross said from the group's headquarters in Geneva.But an official for Afghanistan's opposition alliance known only as Abdullah said he feared thousands of people may have been killed in the quake, which had a preliminary magnitude of 6.9.

The United Nations' disaster relief agency, also in Geneva, said its representatives in the region had reported that 3,000 people may have been buried by debris and landslides caused by the earthquake.

The quake was centered in a remote, mountainous area 45 miles west of Faisabad, the capital of Badakhshan province, the U.S. Geological Survey in Golden, Colo., said.

A plane carrying medical supplies to quake victims was unable to land late Saturday, the Red Cross official said on condition of anonymity.

In February, a devastating earthquake in the same region killed 2,300 people and left thousands of people homeless.

The hardest hit area in Saturday's quake was Shari Basurkh, a town 24 miles west of Faisabad and close to the epicenter, according to the anti-Taliban alliance, which controls the region.

"We think maybe 3,000 people were killed in Shari Basurkh," Abdullah told The Associated Press in a telephone interview from his headquarters.

The remoteness of the region made it virtually impossible to verify the death toll.

Abdullah said the airport closest to the devastation is in Faisabad. The airstrip is currently used by both the United Nations and the International Committee of the Red Cross.

Jacques Tremblay of Doctors without Borders, contacted in the northern city of Mazar-e-Sharif, said he had reports of four dead in Rustaq, an area heavily damaged by a powerful earthquake in February.